Recently, fluorescent materials have attracted increasing attention for biological applications owning to their great sensitivity, high resolution and excellent selectivity. However, traditional fluorescent luminogens often suffer from aggregation-caused quenching (ACQ) effect due to strong π-π stacking, and the emission could be largely quenched in aqueous solutions. In contrast, fluorophores with aggregation-induced emission (AIE) properties exhibit intense emission in the aggregation state due to the restriction of their molecular motions, making them more favorable for biological applications. The main objective of this thesis is to design novel AIE luminogens (AIEgens) based on benzothiadiazole for biological applications including bioimaging, bioconjugation and biosynthesis.

In th...[ Read more ]

Recently, fluorescent materials have attracted increasing attention for biological applications owning to their great sensitivity, high resolution and excellent selectivity. However, traditional fluorescent luminogens often suffer from aggregation-caused quenching (ACQ) effect due to strong π-π stacking, and the emission could be largely quenched in aqueous solutions. In contrast, fluorophores with aggregation-induced emission (AIE) properties exhibit intense emission in the aggregation state due to the restriction of their molecular motions, making them more favorable for biological applications. The main objective of this thesis is to design novel AIE luminogens (AIEgens) based on benzothiadiazole for biological applications including bioimaging, bioconjugation and biosynthesis.

In this thesis, an AIE-active near-infrared (NIR) chemiluminescence (CL) emitter TBL was synthesized by conjugating luminol unit with electron-accepting benzothiadiazole and electron-donating triphenylamine, the prepared AIE nanoparticles can be employed for quantitative (in vitro) and qualitative (in vivo) detection of ¹O₂. The NIR CL emission can penetrate through tissues with a total thickness of over 3 cm and can be utilized for differentiation of tumor and normal tissues. In addition, five AIEgens with activated alkynes were synthesized by rational molecular design, and then reacted with silk fibers through facile metal-free click bioconjugation. A white light-emitting silk was fabricated by simultaneous bioconjugation with red-, green- and blue-emissive AIEgens. The red-emissive AIEgen-functionalized silks were successfully applied for long-term cell tracking and two-photon bioimaging. Moreover, fluorescent bacterial cellulose (BC) was synthesized by incorporation of the glucose-modified AIEgen into cellulose fibers through bacterial fermentation. The real-time visualization of the synthetic process was successfully realized by confocal imaging, which is crucial for further investigating the pathway of bacterial fermentation. Fluorescent electrospun nanofiber mat was fabricated by incorporating fluorescent BC into polyvinylpyrrolidone (PVP), demonstrating great possibility for flexible display and tissue engineering applications.